1. Technical Field
This invention reltates to a method and an apparatus for mixing or dispersing particles based upon the principle of the contact type electric field curtain.
2. Background Art
A prior contact type electric field curtain is comprised of a train of electrodes and of a dielectric layer placed in close vicinity of or in contact with the electrodes, as disclosed in Japanese Patent Publication Kokoku No. 54-12667 "A method of constructing a contact type electric field curtain and an apparatus with use thereof. The electric field curtain is adapted in operation to permit a lightweight substance on the dielectric layer to have thereon electric charges induced by contact thereof with said electric layer and to be rendered to electrodynamical force afforded by the electric field curtain. The lightweight substance is hereby repelled and driven.
Referring FIG. 9, the situation described above is illustrated.
Electrodes a, which are rod-shaped or donut-shaped, for forming an electric field curtain are aligned, and spared from each other. Alternating voltage b is applied between the adjacent electrodes for forming alternating non-uniform electric field having electric force lines indicated by dotted lines c around the respective electrodes a. The alternating non-uniform electric field changes its magnitude and direction with respect to space, while with respect to time it changes its direction sinusoidally. As charged particles approach the alternating nonuniform electric field, the particles are under influence of alternating electric force along the line of electric force, c and hence are forced to oscillate substantially along the curved line of electric force c, whereby the charged particles are rendered to pulsating, outward centrifugal force which is perpendicular to the lines c each half period of the oscillation. Those particles are thus subjected to mean centrifugal force Fc.
Each particles is subjected, at a location close to the electrode a where the electric field is stronger, to the electric force oriented to go away from the electrode a while being subjected, at a location far from the electrode a where the electric field is weaker, to the electric force oriented toward the electrode a. This is because the particles oscillate in a viscous medium. Either way, as a result of difference therebetween, the particle is rendered to mean gradient force Fg directed along the line of electric force, c going away from the electrode a.
The mean centrifugal force Fc is produced owing to spatial change (curved configuration) of the direction of the electric force line c, while the gradient force Fg being produced owing to a spatial change of the density of the lines c (a gradient of electric field intensity). Both are produced because of the electric field being non-uniform and alternate. Thus, the particle is subjected to composite force formed thereof, i.e., electrodynamic replusion force Fr in the direction going away from the electrode train.
The particles adhering to the dielectric layer when the latter is taken into the electric field are charged immediately with electricity on the basis of the principle of the contact charge and forced to float from the dielectric layer owing to the aforementioned electrodynamical replusion force. Such a contact type electric field curtain apparatus finds its application in electrostatic precipitators, electrostatic coating booths, and electrostatic guns, where particles have to be swept off or moved by said repulsion force.
The present inventors have devised the present invention taking notice of a fact that any particle present in the action area of the electric field curtain is subjected to violent disturbance.